Am I correct in understanding that O2 sensors are not part of this DTC?

 

These codes are causing the MIL light to come on. (1997 Expy). Where should I start. I do not have a factory manual yet.

Thanks

 

They will detect the condition (lean I believe), or a faulty sensor could give a lean reading when there is no lean condition, but they probably aren't the cause.

 

Oxygen sensors, both are bank one - too lean

 

A faulty O2 sensor should bring on more than just these codes. Do you also have a rough idle? I would bet you have a leak in your PCV vacuum line. The most common culprit is the rubber elbow at the extreme rear, top, center of the engine. It is hard to see but you can feel it. It tends to dry out and rot. Follow the vacuum line from the PCV valve to the back of the engine and check for leaks. This is easy to check and cheap to repair. Bring the old one into the Ford parts guy and he will know exactly what it is. It is a common problem. Don't change your O2 sensors, yet. $30 or $50 depending on which engine you have. You can change it yourself without a manual.

 

There's lots of info here on those codes if you search. I did. 0171 and 0174 indicate your engine has gone full rich to compensate for a lean condition. I cleaned air filter (K&N), changed fuel filter, changed pcv and hose unit, checked for vac leaks....of course reseting the check engine light each sequence. It would stay off until I got out on the interstates at speed then come back on with the same codes. I was about ready to go to the 02 sensors when I saw something on this site about MAF sensors. I opened up the intake and sprayed the MAF with some electric motor cleaner. That kept the check engine light off for a few months. So, when it came back on I replaced the MAF sensor thing. That was about 10000 miles back and no light yet....

 

I will try out the PVC elbow over the weekend. I'll post the results. Thanks for everyones input.

 

Are these codes covered under warranty? My 03 EB has 32K miles. A friend of mine hooked up the truck to his machine and those codes came back (I wanted to see what was wrong before I brought it in to Ford). I have an appt. with Ford for Friday. I hope they don't pull a fast one and turn off the Service Engine Soon light and send me on my merry way since I have 4k left on the original warranty (I did purchase the extended warranty from them).
Ammie

 

3/36 warranty coverage should apply. No reason it wouldn't.

Steve

 

I changed the complete PVC hose assembly (part #F75Z 6C324 JA). The old one had a hole exactly where JPROP said it would be. So far no more MIL light. Thanks for everyones help. The part cost $26.00 at the dealer and comes with a new PVC attached.

Paul